Apparatus and method for depositing fibrous elements in the manufacture of fibrous structures



June 12. 1956 J. D'A. CLARK ETAL. 2,749,576

APPARATUS AND METHOD FOR DEPOSITING FIBROUS ELEMENTS IN THE MANUFACTURE OF FIBROUS STRUCTURES Filed Oct. 22, 1954 2 Sheets-Sheet 1 IN VEN TOR.

June 12, 1956 J. D'A. CLARK ETAL 2,749,576

APPARATUS AND METHOD FOR DEPOSITING FIBROUS ELEMENTS IN THE MANUFACTURE OF FIBROUS STRUCTURES Filed Oct. 22, 1954 2 Sheets-Sheet 2 IN V EN TOR.

United States Patent APPARATUS AND METHOD FOR DEPOSITING FIBROUS ELEMENTS IN THE MANUFACTURE OF FIBROUS STRUCTURES James DA. Clark, Longview, Wash., and Robert D. Lambert, Sandpoint, Idaho, assignors to Changewood Corporation, Chicago, 11]., a corporation of Illinois Application October 22, 1954, Serial No.- 464,102

14 Claims. (Cl. 19-156) This invention relates to the manufacture of non-woven fabrics of fibrous material and it relates more particularly to apparatus for use with staple fibers of substantial lengths in the manufacture of mats, batts and'non-woven webs which are substantially free of fibrous aggregates orfiber bundles and in which the fibrous elements are uniformly distributed throughout the structure and interfelted one with another in a manner to resist delamination and separation in the fibrous structures formed.

This invention has primary application in the processing of fibrous materials characterized by a tendency to form aggregates or entanglements upon contact with each other, such as occurs with long fine fibers, cotton, or crimped long staple fibers of the monofilament type such as are formed by attenuation of synthetic resinous polymers, very fine glass wool fibers, long slag wool and other siliceous fibers, animal or flax fibers, such as flax straw which may contain lengths of undecorticated straw or threads or strings of flax that behave like long cotton threads. Fibrous structures of the type produced in accordance with the practice of this invention, if of sufficient thickness, will have enough cohesion of its elements for direct use as insulation material or they may be used as a non-woven fabric or as a base for coated fabrics or reinforced plastics or combined with resinous materials for molding under heat and pressure into panels or boards.

This invention is an improvement over the method described and claimed in the copending application Ser. No. 371,055, filed July 29, 1953, and entitled Method and Means for Felting Fibrous Elements, wherein description is given of mechanical means for distributing fibrous elements which are substantially incapable of cohesion or aggregation one with another upon contact and therefore are capable of retaining their individuality to enable the use of gravitational flow alone for the deposition of the separated elements in the manufacture of fibrous structures. When separated fibrous elements capable of cohering or felting together are processed in apparatus of the type described, the separated fibers are incapable of retaining their individuality andquickly form into aggregates of substantial dimension which prevent the uniform distribution of fibers in the fibrousstructure and large aggregates may find their way into the fibrous structure formed to constitute imperfections therein.

To the present, means have not been available for satisfactorily handling fibers of the type described characterized by a high ratio of length to thickness, such as very fine glass fibers or cotton, wool or other staple fibers which tend to form aggregates. Various means have been employed, such as the dispersion of fibers from a parent web tangentially along a roll where both the web and the roll have widths corresponding to the structure to be formed, but satisfactory results have not been available since there have been difficulties in securing adequate dispersion and variations in the weight of fibers in various areas of the parent web or variations in weight of the body of the ice elements of the web being dispersed across the roll are directly reflected in the felted structure.

Instead of dispersion over a width from a corresponding parent web, attempts have also been made to disperse fibers from a point source as directly from spinnerets in conjunction with the attenuation or formation of fibers from molten streams of glass or slag or from synthetic resinous materials or from a pipe through which pulp fibers are sprayed laterally into a chamber through which the fibers fall gravitationally and often in response also to suction, onto a collecting surface at the bottom of the chamber. While the latter system circumvents many of the objectionable characteristics of the Web process, the uniformity of the felted structure then depends chiefly upon the uniformity with respect to distribution of the dispersed fibers during passage from the inlet point to the collecting surface upon which the fibers are deposited to form the fibrous structure. With fibrous elements of variable mass or with fibers that tend to form mutual aggregates, it is difiicult to achieve and maintain a uniform fiber distribution throughout the chamber since the heavy or combined elementsmove through a different trajectory and at a different sustained velocity than the more separated fibers with the result that the fibrous elements of greater mass cross the paths of other fibers to form still larger accretions. As a result, the structure that is formed becomes pitted and loaded with fiber agglomerates and is characterized by relative non-uniformity in fiber distribution especially with long fibers and often even with relatively short fibers of the clinging type.

It is an object of this invention to provide an improvement in a device of the type described for depositing fibrous elements in the manufacture of fibrous structures audit is a related object to produce a felter of the type described which is adapted for depositing into fibrous structures, relatively long thin fibers of the type which tend to cling to each other and aggregate or agglomerate uponcontact and which is effective in providing a fibrous structure having a uniform distribution of fibers and which is relatively free from areas with fiber deficiencies and other other areas with fiber aggregates.

Another object is to provide apparatus for producing a structure of the type described which is simple in construction and easy in operation for the manufacture of endless lengths of mats, batts or non-woven fabrics composed of substantially separated fibers and wherein the fibrous elements are interfelted in a manner to resist delamination and which have sufficient cohesion for selfsupport, if desired, in its handling for further processing in the manufacture of insulation, non-woven fabrics or. for its use in the molding of reinforced plastics, boards or panels.

It is a further object of this invention to provide a method for felting long staple fibers into a uniform web upon a collecting surface; to control the thickness of the deposit forming the web in spaced linear zones across its width; to deposit the fibrous elements upon the collecting surface with minimum disturbance of adjacent elements or elements previously deposited thereon; to deposit the fibers in an endless layer of substantially uniform thickness upon a collecting surface moving at a constant rate and at a uniform speed; and to accomplish these objeclives without causing the fibers to become entangled with other fibers or with parts of the processing equipment.

A still further object is to provide apparatus for use in a method of the type described which provides for the uniform deposition of fibers across the width of a collecting surface and which is substantially free of orifices which might become obstructed and which is relatively free of moving parts which might cause entanglement of fibers prior to their deposition during formation of the fibrous structure and it is a related object to provide a novel nonwoven web composed of long fine fibers wherein the web is characterized by uniformity in fiber concentration and distribution and by isotropic felting in the plane of the structure and the absence of excessive amounts of fiber aggregates.

These and other objects and advantages of this invention will hereinafter appear and for purposes of illustration, but not of limitation, embodiments of the invention are shown in the accompanying drawings in which Figure l is a side elevational view of apparatus embodying features of this invention;

Figure 2 is a sectional view taken substantially along the line 22 of Figure 1;

Figure 3 is a fragmentary sectional view taken substantially along the line 33 of Figure 1;

Figure 4 is a top plan view of a fragmentary portion of the distributor apparatus showing a modified form for fiber distribution;

Figure 5 is a fragmentary view showing a further modification in the structure illustrated in Figure 4;

Figure 6 is a sectional view taken substantially along the line 66 of Figure 5, and

Figure 7 is a schematic elevational view of a still ther modification in a distributor head.

As illustrated in the drawing, apparatus of the type furembodying features of this invention comprises a means for introducing a large volume of air and substantially separated fibers 10 into the upper inlet end 11 of a feed chute 12 having its outlet 13 at the lower end in communication with the inlet 14 of a distributor head 15 of the type described in the aforementioned copending application Ser. No. 371,055. Various means, such as a hammermill type of disintegrator or disperser, may be employed for introducing separated fibers and air into the chute leading to the distributor head, or a disperser of the type described in the copending application Ser. No. 394,435, filed November 25, 1953. A layer of fibrous material is advanced on an endless belt 16 at a predetermined but adjustable rate into a fiber dispersing couple formed of a supporting roller 17 and a brush roller 18 rotating at high peripheral speed by comparison with the roller 17 so that the web is engaged at its leading edge by the bristles extending radially from the brush roller for separation of the individual fibers which are thrown by centrifugal force from the ends of the bristles into the feed chute 12 upon separation. In operation, the brush roller rotating at high peripheral speed functions also as an impeller or blower which generates the movement of a large volume of air as a stream moving away from the fiber dispersing couple and into which the substantially completely separated fibers are entrained for dispersion and whereby the separated fibers are carried at least part 27 and a bottom wall 22 which has a plurality of openings 28 in substantially equally spaced apart relation each of which forms an inlet to separate tubular members 29 in the form of down pipes which terminate adjacent the upper surface of a collecting member 30 upon which the fibrous elements are deposited to form the fibrous structure 31. The outlet ends of the down pipes are arranged in side by side relation across the collecting member in at least one and preferably a number of longitudinally spaced apart rows. For this purpose, the lower end portions 32 of the down pipes 29 are secured to rods 33 which extend across the collecting member as by means of brackets in the form of tubular sleeves 34 rigid with the down pipes and slidably secured on the cross bars 33 for lateral adjustment to a desired position for uniform distribution and in which position the sleeves may be secured as by means of setscrews 35.

The collecting member is preferably formed of an end- I less foraminous screen 30 which operates about end rollers way through the distributor apparatus without such contact one with another as would cause excessive aggregation. Where fibers have an especial tendency to clot or aggregate, additional air may be supplied with the fibers to the dispersing means employed, from a blower, and conveyed with the separated fibers into the distributor head.

Briefly described, the mechanical distributor comprises a tubular member 19 mounted for rotational movement with its upper inlet end portion 14 in communication with the outlet end of the feed chute 12 and in alignment with the axis of rotation of the tube while its outer end portion 20 at the lower end is offset from the axis with an inclined curvilinear portion 21 in between. The outlet end portion 20 which moves through a circular path about the axis communicates with the bottom wall 22 i 36 and 37 located in advance of and beyond the fiber depositing zone between the down pipes and one of the rollers is adapted to constitute a driving member operatively connected by means of a belt 38 or a chain to a driving motor 39 with means for adjusting the linear speed of the screen depending upon the amount of fibers to be deposited and the thickness of the fibrous structure to be formed. A tension roller 40 engages the lower flight of the endless screen to maintain the desired operating relation.

One of the important concepts of this invention which enables the use of apparatus of the type described for long thin fibers and fibers capable of agglomeration upon contact resides in the means for assisting gravitational force to maintain constant movement of the fibers in their separated relation downwardly through the tubular distributing member 19 and through the down pipes 29 for deposition onto the screen to form the fibrous structure. For this purpose, air flow in substantial amounts from the inlet end 12 to the outlet end 32 is provided in the tubular members to carry the separated fibers dispersed in the air stream through the tubular members for deposition onto the collecting surface. When air in sufiicient volume flows through the tubular members, the possibility for contacting relation to form fiber bundles and agglomerates is markedly reduced and entrapments which lead to agglomeration of fibers and interference with the desired flow through the distributing elements is substantially completely eliminated.

To accommodate the flow of air in the desired volumes through the distributor tubes for conveyance of the fibers dispersed therein in substantially separated relation, means are provided for drawing the large volumes of delivered air through the screen from the underside in alignment with the outlet openings of the down pipes and preferably in coordination with the introduction of fibers therein for delivery to the top flight of the collecting screen. As shown in the drawing, suction means operative through the underside of the collecting screen comprises suction boxes 41 extending crosswise of the screen beneath each row of down pipes. Air is withdrawn through the suction boxes through conduits 42 in communication with means for extracting air such as by a suction pump or a vacuum source. When relatively thick batts are made at a low speed, it may be desirable in order to make greater utilization of the suction to adjust the vacuum crosswise of the box to limit the formation of vacuum beneath the down pipes in which fibers are being or are about to be conveyed. For this purpose, each suction box is formed with an elongate opening 43 across the top corresponding to the width of the row of down pipes and contains .a rotatable sleeve 44 formed with a helical slot 45 through the outer wall with means operatively engaging the end portion of the sleeve, such as sprockets 46 for rotating the sleeves within the suction box, as by means of a driving motor such as the motor 24 which coordinatethe turning movement of the sleeve with the rotational movement of the tubular distributor to achieve a suction in those pipes about to be put in communication with the distributor and preferably over a sufficiently greater period of time to enable the fibrous elements to be substantially completely exhausted from the corresponding down pipes before the suction means is cut off. This coordinated relationship with lagging suction may be achieved by proper curvature and Width of the helical slot 45 which functions to conceal all but the progres- -sively laterally moving openings communicating with the slot of the vacuum trough.

It will be apparent that by adjusting the relationship of the helical opening'45 beneath the outlets of the down pipes '29 with the position of the outlets from the distributor tube 19, a concentrated exhaust may be caused to exist over the area of deflecting screen beneath the outlet of each down pipe during passage of air entrained fibers therein.

In operation, the separated fibers are introduced into the chute 12 leading to the inlets of the tubular distributor member 19 along with a relatively large volume of air in which the separated fibers become substantially'completely dispersed. Usually sufiicient air will be induced to travel with the separated fibers when separating and dispersing means forming the fiber dispersing couple of the type described are employed, especially when the couple is housed within a shroud or casing. Additional air may be supplied if desirable for proper dispersion. The air-borne fibers travel from the inlet end of the tubular distributor to the outlet end which serves to parcel out the fibers in substantially uniform quantities into the openings 28 in the annular trough 23 during rotational movement.

The air-borne fibers issuing from the tubular distributor pass through the openings in the bottom wall of the trough and into the down pipes for passage therethrough in response to air flow from the inlet and to some extent in response to the extraction of air by the suction means substantially in communication with the outlet from the underside of the separating screen. As the air-borne fibers issue from the outlets of the down pipes, the fibers separate onto the surface of the forarninous collecting screen while the air filters through the screen for passage into the suction boxes. Since the distributor head parcels out the fibers in substantially equal quantities for delivery to each of the openings in the trough, it will be apparent that if the down pipes are arranged in equally spaced apart relation about the trough and if theirlower ends are arranged in a desired side by side relation across the collecting surface, the fibers will be deposited in substantially equal concentrations across the width of the collecting screen. Furthermore, when sufficient air is introduced to carry the dispersed fibers to the inlet, they remain substantially individually dispersed during their passage through the distributor elements to the collecting surface upon which they will deposit in an interfelted relation to provide a structure having enough cohesion for its self-support.

It is desirable to adjust the degree of vacuum in the box corresponding to the amount necessary to hold the deposited fibers in their interfelted relation on the screen during passage through the fiber depositing zone. It is desirable to maintain the applied vacuum to a minimum so as to assist the fibers issuing from the down'pipes to integrate and interfelt with the fibers previouslydeposited. This interfelting relation is further assisted by the application of vacuum beneath the collecting wire in an intermittent manner as previously described in response to operation of the tubular member 44 with a helical slot within the vacuum trough since the alternating suction sequentially compresses the deposited fibers followedby expansions during periods wherein vacuum is not present thereby to effect better felting of the fibers which have been deposited.

Not infrequently, when usedfor the deposition of long fibers of the type described, some fibers may become entrapped as by draping over the portions formed between the openings 28 and the bottom wall of the distributor trough 23. The draped fibers collect other fibers to form agglomerates which subsequently may become free and pass with the other fibers to form undesirable inclusions in the fibrous structure. The formation of such fiber bundles has been avoided by modification to provide a moving surface forming the partitions of the bottom wall 22 between the openings 28 as by means of rollers 50 mounted for turning movement about a radially disposed horizontal axis on shafts 51 having separate but preferably interconnected means for rotation of same. For example, each shaft 51 may be provided with a pair of pulleys 52 and 53 on the outer ends thereof beyond the trough With belts or the like operatively connecting one pulley with another on an adjacent shaft and having a common drive in the form of a gear motor 54 for actuating same. Upon operation, any fibers deposited on the rollers 50 between the openings will be displaced into the openings defined thereby by centrifugal action or as the roller scrapes against the belts, or by other means for removal such as supplementary doctor blades or air jets.

When a large number of down pipes are employed in cooperation with a rapidly rotating distributor head, the period of time that the outlet of the tubular distributor is in communication with each of the openings leading the down pipes from a separate source and supplemental to the air in which the fibers are dispersed after t. the distributor has passed beyond the openings as by means of a centrifugal fan 55 operated by a motor 56 to form an assembly joined to the trailing wall of the tubular distributor for movement therewith in the area immediately beyond the outlet end of the distributor tubing.

Instead of or in addition to adding the supplementary air subsequent to the passage of the end of the distributor tubing over the openings leading to the down pipes, the additional air may be introduced into the lower end of the distributing tube, such for example as at the position indicated by the dotted lines 67 in Figures 5 and 6. When so arranged, the supplementary air will function as an ejector to cause additional air to be drawn past the fiber depositing couple further to dilute the fibers in the air stream so that they will tend to form agglomerates less readily prior to deposition upon the collecting screen.

In a modified form of distributor, pipe assembly 57, having an outlet at 58 and an inlet at 59 is caused to rotate on a vertical spindle from motor driven gearbox 60. Adjacent the inlet 59 and carried by the pipe assembly is a motor driven blower 61 supplied with electric power as by means of collector rings 62. The blower discharges high velocity air across the opening as the pipe assembly rotates which serves to draw in any material fed to the opening and discharge it through the outlet 58 successively into the down pipes 29 from annular trough 23 as before. The fibrous material 63 is fed into the opening at a constant rate by any suitable dispersing means such as rolls 17 and 18 as already described.

It will be apparent that instead of feeding fibers to the distributor device by means of a fiber dispersing couple, other means may be employed such as spinnerets to spin fibers from a solution of a resin or a melt such as glass, in a well known manner. The spun fibers would be carried down and uniformly deposited upon the collecting screen as previously described. For such purposes, it may be desirable to elongate the openings 28 in the bottom wall 22 of the annular trough and to employ down pipes 29 of rectangular cross section having arcuate openings at the upper end to fit the openings of the trough. With these provisions, there would be relatively little breakage of the spun fibers even when formed of such low strength materials as slag. Mineral wool batts so formed would not only be composed of long fibers deposited in uniform concentration but would have a higher than normal degree of strength and stiffness because the fiber lengths have been preserved. To prevent blowing of the fibers away from the fiber depositing zone, the amount of air withdrawn from the underside of the collecting screen should be slightly greater than the amount of air passing with the fibers through the down pipes to cause the static pressure in the felting zone to be slightly subatmospheric causing a slight inflow of air into the fiber depositing zone from the adjacent atmosphere. This concept disclosed in copending application Serial No. 61,674, filed November 23, 1948, enables the area between the ends of the down pipes and the collecting screen to remain open to the atmosphere so that the thickness of the deposited mat may be built up by passing the collecting screen successively beneath a plurality of felting units, each of which may add a lamina of the same or of different fibers or other materials to the deposited fibers on the screen, in the same manner as disclosed in copending application Serial No. 110,212, filed August 13, 1949, now Patent No. 2,698,271.

Solid or liquid binding agents, such as powdered phenolic resins, adhesives or the like, or various fillers, pigments, dyes, fireproofing agents and other modifying agents may be added to the fibers either before they are fed to the apparatus or during or after their deposition onto the collecting surface. The resulting web may be impregnated with liquids or surfaced with discrete materials or sheet materials and thereafter consolidated under heat and pressure into molded structures.

It will be apparent from the foregoing description that we have provided a new and improved method and apparatus for the processing of relatively long and thin fibers and for their deposition to form a uniform web which is relatively free of imperfections and one that is further characterized by its imbricated construction when it is slowly pulled apart.

It will be apparent that the apparatus described not only provides for good control of the uniformity of deposition of fibrous elements across the web but also minimizes the possibility of fibers becoming lodged in restricted openings in the distributing means which might otherwise interfere with the function of the distributor and with the uniform distribution of fibers in the structure that is formed. The conditions employed in the operation of the apparatus described further minimize the opportunity for the dispersed fibers to aggregate and form into strings or clusters prior to their deposition.

The pneumatic system herein described is applicable also to the oscillating distributor mechanism disclosed in the copending application Serial No. 371,055 and it will be apparent that other changes may be made in the construction, arrangement and operation without departing from the spirit of the invention, especially as defined in the following claims.

We claim:

1. In the method for depositing fibers across the surface of a foraminous collecting member moving continually in one direction for the manufacture of endless webs, the steps of introducing the fibers at a uniform rate into the inlet end of a distributor duct, moving the outlet to the other end of the distributor duct continuously and successively into communication with the inlets of a plurality of separate conveyor ducts at a rate to deliver substantially equal amounts of fibers to each, said conveyor ducts having their outlets arranged across and spaced a short distance above the surface of the foraminous collecting member upon which the fibers are received to form the fibrous web on the surfaces thereof, introducing air in large volumes with the fibers into the inlet end of the distributor duct whereby the fibers remain dispersed and are carried by the air stream through the distributor and conveyor duct members, and withdrawing a greater volume of air from the underside of the foraminous collecting member beneath the conveyor duct members than issues from the conveyor ducts.

2. In the method for depositing fibers across the surface of a foraminous collecting member moving continually in one direction for the manufacture of endless webs, the steps of introducing the fibers at a uniform rate into the inlet end of a distributor duct, moving the outlet to the other end of the distributor duct continuously and successively into communication with the inlets of a plurality of separate conveyor ducts at a rate to deliver substantially equal amounts of fibers to each, said conveyor ducts having their outlets arranged across and spaced a short distance above the surface of the foraminous collecting member upon which the fibers are received to form the fibrous web on the surfaces thereof, introducing air in large volumes with the fibers into the inlet end of the distributor duct whereby the fibers remain dispersed and are carried by the air stream through the distributor and conveyor duct members, and withdrawing air from the underside of the foraminous collecting member in the area corresponding to that covered by the outlet end of the conveyor duct into which fibers are introduced.

3. In the method for depositing fibers across the surface of a collecting member moving continually in one direction for the manufacture of endless webs, the steps of introducing the fibers at a uniform rate into the inlet end of a distributor duct, moving the outlet to the other end of the distributor duct continuously and successively into communication with the inlets of a plurality of separate conveyor ducts at a rate to deliver substantially equal amounts of fibers to each, said conveyor ducts having their outlets arranged across and spaced a short distance above the surface of a foraminous collecting member upon which the fibers are received to form the fibrous web on the surfaces thereof, introducing air in large volumes with the fibers into the inlet end of the distributor duct whereby the fibers remain dispersed and are carried by the air stream through the distributor and conveyor duct members, and introducing additional volumes of air into the inlet ends of the conveyor ducts subsequent to the passage of the outlet end of the distributor duct in communication therewith for the introduction of fibers.

4. The method as claimed in claim 2 in which the withdrawal of air from the underside of the foraminous conveying member progresses crosswise thereof to correspond to and in timed relation with the introduction of fibers into said ducts by the distributor member.

5. Apparatus for felting substantially separated fibers to form a uniform web across a moving foraminous collecting surface comprising a distributor duct having an inlet and an outlet, means for feeding fibers at a uniform rate into the inlet and for feeding large volumes of air concurrently with the fibers into the inlet for dispersion of the fibers therein, a plurality of separate conveyor ducts each having an inlet end and an outlet end the latter being positioned in at least one longitudinally spaced row across the foraminous collecting surface, and means for moving the outlet of the distributor duct continually and successively into communication with the separate inlets of the conveyor ducts to introduce substantially equal amounts of fibrous elements into each whereby the fibers are carried by the air through the ducts for deposition in uniform concentration across the collecting surface upon the issuance from the outlets of each conveyor duct.

6. Apparatus for felting substantially separated fibers to form a uniform web across a moving foraminous collecting surface comprising a distributor duct having an inlet and an outlet, means for feeding fibers at a uniform rate into the inlet and for feeding large volumes of air concurrently with the fibers into the inlet for dispersion of the fibers therein, a plurality of separate conveyor ducts each having an inlet end and an outlet end the latter being positioned in at least one longitudinally spaced row across the foraminous collecting surface, means for moving the outlet of the distributor duct continually and successively into communication with the separate inlets of the conveyor ducts to introduce substantially equal amounts of fibrous elements into each whereby the fibers are carried by the air through the ducts for deposition in uniform concentration across the collecting surface upon issuance from the outlet of each conveyor duct, and means for withdrawing air from the underside of the foraminous collecting surface to maintain substantially complete delivery of the air entrained fibers introduced into each of the ducts to the foraminous collecting surface.

7. Apparatus for felting substantially separated fibers to form a uniform web across a moving foraminous collecting surface comprising a distributor duct having an inlet and an outlet, means for feeding fibers at a uniform rate into the inlet and for feeding large volumes of air concurrently with the fibers into the inlet for dispersion of the fibers therein, a plurality of separate conveyor ducts each having an inlet end and an outlet end the latter being positioned in at least one longitudinally spaced row across the foraminous collecting surface, means for moving the outlet of the distributor duct continually and successively into communication with the separate inlets of the conveyor ducts to introduce substantially equal amounts of fibrous elements into each whereby the fibers are carried by the air through the ducts for deposition in uniform concentration across the collecting surface upon the issuance from the outlets of each conveyor duct, and means for withdrawing air from the underside of the foraminous collecting surface in areas corresponding to and in timed relation with the introduction of fibers into the conveyor ducts.

8. Apparatus for felting substantially separated fibers to form a uniform web across a moving foraminous collecting surface comprising a distributor duct having an inlet and an outlet, means for feeding fibers at a uniform rate into the inlet and for feeding large volumes of air concurrently with the fibers into the inlet for dispersion of the fibers therein, a plurality of separate conveyor ducts each having an inlet end and an outlet end the latter being positioned in at least one longitudinally spaced row across the foraminous collecting surface, means for moving the outlet of the distributor duct continually and successively into communication with the separate inlets of the conveyor ducts to introduce substantially equal amounts of fibrous elements into each whereby the fibers are carried by the air through the ducts for deposition in uniform concentration across the collecting surface upon issuance from the outlet of each conveyor duct, means for withdrawing air from the underside of the foraminous collecting surface to maintain substantially complete de- 10 livery of the air entrained fibers introduced into each of the ducts to the foraminous collecting surface, and means for introducing additional vciumes of air into the inlets of the conveyor ducts immediately following communication thereof with the outlet end of the distributor duct.

9. Apparatus for felting fibers to form a uniform web across a moving collecting surface comprising a distributor in the form of an upwardly disposed duct having the inlet in the upper end and the outlet in the lower end, a circular trough having a plurality of equally spaced apart openings in a wall thereof in communication with the outlet end of the distributor duct, a plurality of separate down pipes having inlet ends in communication with the outlet ends of the openings and having outlet ends uniformly spaced crosswise of the foraminous collecting surface in one or more longitudinally spaced apart rows, means for moving the outlet end of the distributor duct about the trough for successive communication with the inlet ends of the down pipes, means for feeding fibers at a constant and uniform rate into the inlet end of the distributor duct, means for introducing large volumes of air concurrently with the fibers into the inlet ends of the distributor duct whereby the fibers are dispersed in the air stream and carried thereby downwardly through the duct and down pipes, and means for moving the foraminous collecting surface continually in a direction perpendicular to the rows of down pipes for receiving the fibers issuing therefrom in interfelting relation to form a web on the surfaces thereof.

10. Apparatus as claimed in claim 9 which includes means for adjusting the outlet ends of the down pipes crosswise of the foraminous collecting surface.

11. Apparatus as claimed in claim 9 which includes means for withdrawing air from the underside of the foraminous collecting surface in areas corresponding to and in timed relation with the introduction of air and fibers into the inlet ends of the down pipes.

12. Apparatus as claimed in claim 9 which includes means forming the bottom wall of the trough between the openings which prevent entrapment of fibers thereon comprising rollers rotating in the direction of the openlugs.

13. Apparatus as claimed in claim 9 which includes means operative with the outlet end of the distributor duct for introducing additional volumes of air into the inlet end of the down pipes after passage of the distributor duct thereover.

14. Apparatus as claimed in claim 9 which includes means forming a cut-off blade between the openings to sever any long fibers spanning the openings and displacing fibers from the surfaces of the rolls into the openings by rotating the rollers.

Simpson Feb. 4, 1941 Drill Apr. 27, 1943 

1. IN THE METHOD FOR DEPOSITING FIBERS ACROSS THE SURFACE OF A FORAMINOUS COLLECTING MEMBER MOVING CONTINUALLY IN ONE DIRECTION FOR THE MANUFACTURE OF ENDLESS WEBS, THE STEPS OF INTRODUCING THE FIBERS AT A UNIFORM RATE INTO THE INLET END OF A DISTRIBUTOR DUCT, MOVING THE OUTLET TO THE OTHER END OF THE DISTRIBUTOR DUCT CONTINUOUSLY AND SUCCESSIVELY INTO COMMUNICATION WITH THE INLETS OF A PLURALITY OF SEPARATE CONVEYOR DUCTS AT A RATE TO DELIVER SUBSTANTIALLY EQUAL AMOUNTS OF FIBERS TO EACH, SAID CONVEYOR DUCTS HAVING THEIR OUTLETS ARRANGED ACROSS AND SPACED A SHORT DISTANCE ABOVE THE SURFACE OF THE FORAMINOUS COLLECTING MEMBER UPON WHICH THE FIBERS ARE RECEIVED TO FORM THE FIBROUS WEB ON THE SURFACES THEREOF, INTRODUCING 